The present invention relates to an assisted manual designation system for an optical or optronic radar director theodolite gain device.
It is known that the operation of radar or optronic automatic tracking devices makes it necessary to previously bring the target into the field of said devices which are inter alia of the director theodolite type. This operation, called designation of the target, is performed by an operator or a gun crew member by means of an optical unit having a sight tube mounted on a turret and having two degrees of freedom, for example in elevation and in bearing, with respect to a reference platform.
This platform may or may not be movable, depending on whether the optical unit is on land or on board a ship.
The operating procedure is then as follows: the operator orients the sight tube in the direction of the target to be designated and when the latter is in the aiming axis of the sighting device the operator transmits a "well-directed" signal to the automatic tracking device which then takes over the actual tracking.
Target designation systems can be classified into two categories:
passive systems where the physical strength of the operator enables him to move the turret of the director theodolite to bring the target onto the aiming axis;
active systems where a motor supplies the energy necessary for moving the turret, the operator only controlling the motor.
In a prior art passive system, shown in diagrammatic manner in FIG. 1, the operator moves by his own means on a plateform 1 holding on to a band rail 3 fixed to a base 2, the latter being fixed to the platform.
The mobility of a sight tube 5 is ensured in bearing about an azimuth axis AZ by a rotary member 4 placed between the sight tube 5 and the base 2 and in elevation by the joint 7 between member 4 and 5, the operator, whose eye is shown at 6 in the extension of the aiming axis 8 shown in dotted line form holds the handrail 3 with one hand and uses the other for directing the turret constituted by members 4 and 5, for example by means of the drive member not shown in the drawing.
This type of system has a certain number of disadvantages, common to all passive designation systems.
On the one hand the sight tube has no inertial stability due to mechanical friction and to its articulation in accordance with elevation/bearing axes.
On the other hand it is apparent that for another position 105 of said sight tube the eye of the operator must move to arrive at 106 on the new aiming axis 108. This displacement, as well as those required by the variation in bearing of the turret requires gymnastics on the part of the operator, which is prejudicial to the sighting efficiency. Only a single position of the operator's eye on the rotation axis in elevation would permit a relative immobility, but this is difficult to achieve due to the mechanical articulation necessary, whilst further increasing the above-mentioned shortcoming of lack of inertial stability.
Another disadvantage of passive systems is associated with the fact that there is a manual drive system. The operator, who is not necessarily working under good conditions, for example on a ship subject to roll and pitch may well not coordinate his movements in a satisfactory manner. In particular the very fact of his providing the well-directed signal may make him loose the correct aim at the very time where it must be perfectly performed.
Active designation systems were developed for the purpose of obviating these disadvantages.
In a prior art construction the active designation system is such that the operator is moved by part of the director theodolite which is mobile in bearing, observes the target on a television screen, whose camera is directed in accordance with the aiming axis and has bearing and elevation velocity controls actuating the motors which drive the theodolite turret.
In another prior art active system construction the operator does not move, observes a large portion of space by means of a large field television monitor and remotely controls the theodolite turret by means of a console.
In all prior art active systems there are automatic correction loops in bearing and elevation velocity of the director theodolite turret permitting an inertial stability. Depending on whether the theodolite is on land or on board a ship the velocity pickups are tacho-alternators or rate gyros so as to compensate for the roll and pitch movements in the case of a ship.
However, it is still the operator who controls the turret position. From the automation standpoint consideration must be given to an ergonomic position loop where the operator evaluate the sighting error and acts on the controls in such a way as to reduce said error. Thus, an ergonomic loop is a loop including the operator in its open loop transfer. However, an electromechanical loop is a slaving loop using electromechanical means.
However, the prior art active designation systems using for example television screens and control consoles which are mechanically independant of the turret require very advanced training on the part of the operator, because the various movements which the latter has to perform are not reflex.
Greatest importance is attached to the reflex movement aspect on the part of the operator, because the designation of the target must be very fast, said target being for example an aircraft. Under these conditions the use of a sequence of learned movements represents a loss of efficiency compared with the use of natural reflex movements.